Heater

ABSTRACT

The present invention provides a heater capable of prohibiting failures of a substrate and a heat resistor. The heater of the present invention includes a substrate in a longitudinal shape, a heat resistor formed on the substrate, and an electrode for resistor formed on the substrate and connected to the heat resistor. The heat resistor includes a first elongated portion, and the first elongated portion extends along a long side direction of the substrate and is disposed in a side in a first short side direction, which is one of short side directions of the substrate. A ratio of a distance between the first elongated portion and an edge of the substrate on the first short side direction, to a thickness of the substrate is more than 0 and less than 1.75.

BACKGROUND

The present invention is related to a heater.

heater has been known for a toner fixed in an office automationapparatus (for example, an electronic copier, a facsimile machine and aprinter). Such heater includes a longitudinal shaped substrate and aheat-generating resistor, for example. In this heater, if the heatingcomponent of resistor generates heat, the substrate and the resistorheating component generate thermal stress. In the conventional heaters,there is a poor situation that the substrate and the heating componentfails due to the thermal stress. As the literature regarding the heater,the patent literature 1 is well-known.

BACKGROUND TECHNICAL LITERATURES Patent Literatures

[Patent literature 1] Japanese Patent Application Publication No.2009-193844

BRIEF SUMMARY OF THE INVENTION Problems to be Solved in the Invention

The present invention is carried out based on the above situation, andprovides a heater for preventing a substrate and a heat resistor frombeing damaged.

Technical Means for Solving Problems

In the preferred embodiment of the present invention, thecharacteristics of the heater provided by the present invention includea longitudinal-shaped substrate; a heat resistor, formed on thesubstrate; and an electrode for resistor formed on the substrate and incontact with the heat resistor, wherein the heat resistor includes afirst elongated portion, the first elongated portion extends along along side direction of the substrate and is disposed in one of shortside directions of the substrate, i.e. a first short side direction, anda ratio of a distance between the first elongated portion and an edge ofthe substrate in the first short side direction to a thickness of thesubstrate is more than 0 and less than 1.75.

Effects of the Invention

According to the present invention, the damage to the substrate and theheat resistor can be prevented.

Other features and advantages of the present invention are betterunderstood in the following detailed descriptions with reference tofigures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a device according to the firstembodiment of the present invention.

FIG. 2 is a top view showing a heater according to the first embodimentof the present invention.

FIG. 3 is a top view showing a main portion of the heater according tothe first embodiment of the present invention.

FIG. 4 is a cross-sectional view along the line IV-IV of FIG. 2.

FIG. 5 is an enlarged cross-sectional view showing the main portion ofthe heater according to the first embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view showing the main portion ofthe heater according to the first embodiment of the present invention.

FIG. 7 is a cross-sectional view showing the main portion along the lineVII-VII of FIG. 2.

FIG. 8 is a curve diagram showing the relationship between the distancefrom the heat resistor to an end of the substrate and the endurancetime.

FIG. 9 is a curve diagram showing the relationship between the distancefrom a first elongated portion to a second elongated portion and theendurance time.

FIG. 10 is a top view showing a main portion of a heater according tothe second embodiment of the present invention.

FIG. 11 is a cross-sectional view along the line XI-XI of FIG. 10.

DETAILED DESCRIPTION

In the following descriptions, the preferred embodiments of the presentinvention are specifically illustrated with reference to theaccompanying drawings.

FIG. 1 is a cross-sectional view showing a device according to the firstembodiment of the present invention.

A device 800 shown in the figure is, for example, used for toner fixingin an OA (Office Automation) apparatus (for example, an electroniccopier, a facsimile machine or a printer). The device 800 includes aheater 101, a platen roller 801 and a thermistor 861.

The heater 101 is opposite to the platen roller 801 for allowing thetoner, which is transferred to the heated medium Dc, to be thermallyfixed to the heated medium Dc.

FIG. 2 is a top view showing the heater 101. FIG. 3 is a top viewshowing a main portion of the heater 101, in which a protection layer 7is omitted. FIG. 4 is a cross-sectional view along the line IV-IV ofFIG. 2. FIG. 5 is an enlarged cross-sectional view showing a mainportion of the heater 101. FIG. 6 is an enlarged cross-sectional viewshowing a main portion of the heater 101. FIG. 7 is a cross-sectionalview showing a main portion along the line VII-VII of FIG. 2.

The heater 101 includes a substrate 1, a heat resistor 2, an electrode 5specified for the resistor, and a protection layer 7.

The substrate 1 is in a longitudinal shape. In FIG. 1 to FIG. 7, adirection of a long side of the substrate 1 is set as a long sidedirection X, a direction of a short side of the substrate 1 is set as ashort side direction Y, and a direction of a thickness of the substrate1 is set as a thickness direction Z.

In the present embodiment, the substrate 1 includes an insulatingmaterial. In the present embodiment, the insulating materialconstituting the substrate 1 is ceramics. As this ceramics, aluminumoxide and zirconium oxide can be used, for example.

Preferably, a dimension on the thickness direction Z of the substrate 1,i.e. a thickness T, is 0.4˜1.0 mm, for example. More preferably, thethickness of the substrate 1 is 0.4˜0.6 mm, for example. Under thesituation that the substrate 1 includes the material with small thermalconductivity (for example, aluminum oxide), the thickness of thesubstrate 1 is preferably thinner. In addition, a dimension in the shortside direction Y of the substrate 1, i.e. a short side directiondimension W, is preferably 3.0˜15.0 mm.

The substrate 1 includes a substrate main surface 11, a substrate backsurface 12, a first substrate lateral surface 13, a second substratelateral surface 14, a first substrate end surface 15 and a secondsubstrate end surface 16. The substrate main surface 11, the substrateback surface 12, the first substrate lateral surface 13, the secondsubstrate lateral surface 14, the first substrate end surface 15 and thesecond substrate end surface 16 are all flat.

As shown in FIG. 4, the substrate main surface 11 and the substrate backsurface 12 are disposed on mutually opposite sides in the thicknessdirection Z, and facing to mutually opposite sides. The substrate mainsurface 11 faces to one way of the thickness direction Z. On the otherhand, the substrate back surface 12 faces to the other way of thethickness direction Z. The substrate main surface 11 and the substrateback surface 12 are both long rectangular shapes.

The first substrate lateral surface 13, the second substrate lateralsurface 14, the first substrate end surface 15 and the second substrateend surface 16 shown in FIG. 2 to FIG. 4 all face to the directioncrossing with the thickness direction Z of the substrate 1. The firstsubstrate lateral surface 13 and the second substrate lateral surface 14are disposed on the plane of the end portion of the substrate 1 in thelong side direction.

The heat resistor 2 shown in FIG. 1 to FIG. 7 is formed on the substrate1. The heat resistor 2 is connected to the substrate 1. In addition, “acertain object formed on another object” recited in the presentapplication includes “the situation that certain object is not connectedto another object” in addition to “certain object is connected to otherobject”. The heat resistor 2 generates heat through flowing current. Theheat resistor 2 includes a resistor material. As the resistor materialconstituting the heat resistor 2, AgPd can be used, for example. Asother materials constituting the heat resistor 2, nickel-chromium alloyor ruthenium oxide can be used, for example. The thickness (thedimension in the thickness direction Z) of the heat resistor 2 is, forexample 5˜15 nm. The heat resistor 2 is formed by printing, for example.The heat resistor 2 is formed on the side of the substrate main surface11 in the substrate 1. In the present embodiment, the heat resistor 2 isconnected to the substrate main surface 11.

As shown in FIG. 2 to FIG. 4, the heat resistor 2 includes a firstelongated portion 21 and a second elongated portion 22.

The first elongated portion 21 extends along the long side direction Xof the substrate 1. The first elongated portion 21 is formed in a firstshort side direction Y1 side (a lower side in FIG. 3) of the short sidedirection Y of the substrate 1. The first elongated portion 21 is formedfrom one end of the long side direction X of the substrate 1 to theother end. The length of the first elongated portion 21 is more than50%, preferably more than 70%, and more preferably more than 80% of thedimension in the long side direction X of the substrate 1. The firstelongated portion 21 is connected to the substrate 1, and in the presentembodiment, is connected to the substrate main surface 11.

The second elongated portion 22 extends in a longitudinal shape alongthe long side direction X of the substrate 1. The second elongatedportion 22 is formed in a second short side direction Y2 side (an upperside in FIG. 3) of the short side direction Y of the substrate 1. Thesecond elongated portion 22 is formed from one end of the long sidedirection X of the substrate 1 to the other end. The length of thesecond elongated portion 22 is more than 50%, preferably more than 70%,and more preferably more than 80% of the dimension in the long sidedirection X of the substrate 1. The second elongated portion 22 isconnected to the substrate 1, and in the present embodiment, isconnected to the substrate main surface 11. The second elongated portion22 and the first elongated portion 21 are separated from each other inthe short side direction Y of the substrate 1. The second elongatedportion 22 and the first elongated portion 21 are parallel to eachother.

As shown in FIG. 4 to FIG. 6, the distance between the first elongatedportion 21 and the edge of the substrate 1 in the first short sidedirection Y1 is a distance L1. In addition, a distance between thesecond elongated portion 22 and the edge of the substrate in the secondshort side direction Y2 is a distance L2. Additionally, a distancebetween the first elongated portion 21 and the second elongated portion22 in the short side direction Y is a distance L3.

The ratio of the distance Li to the thickness t of the substrate 1 ismore than 0 and less than 1.75, and preferably more than 0.05 and lessthan 1.75. The distance L1 is 0 mm-0.7 mm, and preferably 0.05 mm-0.7mm. In addition, the ratio of the distance L2 to the thickness t of thesubstrate 1 is more than 0 and less than 1.75, and preferably more than0.05 and less than 1.75. The distance L2 is 0 mm-0.7mm, and preferably0.05 mm-0.7 mm. In addition, the preferred lower limit of the distanceL1 and the distance L2 is 0.05 mm since the fabrication of the firstelongated portion 21 and the second elongated portion 22 or theprotection layer 7 is limited.

The ratio of the distance L3 to the thickness t of the substrate 1 ismore than 0 and less than 9.5, and preferably more than 0.05 and lessthan 9.5. The distance L3 is more than 0 mm and less than 3.8 mm.Preferably, the distance L3 is 0.05 mm-3.8 mm.

The ratio of the distance L1 to the short side direction dimension W ismore than 0 and less than 0.23, and preferably more than 0.003 and lessthan 0.23. The ratio of the distance L2 to the short side directiondimension W is more than 0 and less than 0.23, and preferably more than0.003 and less than 0.23. The ratio of the distance L3 to the short sidedirection dimension W is more than 0 and less than 1.27, and preferablymore than 0.003 and less than 1.27.

The electrode 5 specified for the resistor shown in FIG. 2 and FIG. 3 isformed on the substrate 1. The electrode 5 specified for the resistor isconnected to the substrate 1. The electrode 5 specified for the resistoris used for providing the power outside the heater 101 to the heatresistor 2. The electrode 5 specified for the resistor includes aconductive material. As the conductive material constituting theelectrode 5 specified for the resistor, Ag can be used, for example. Thethickness (the dimension in the thickness direction Z) of the electrode5 specified for the resistor is, for example, 5˜15 mm. The electrode 5specified for the resistor is formed by printing, for example. In thepresent embodiment, the electrode 5 specified for the resistor is formedat the substrate main surface 11 side in the substrate 1. The electrode5 specified for the resistor is connected to the substrate main surface11. As shown in FIG. 4, a part of the electrode 5 specified for theresistor is overlapped with and connected to a part of the heat resistor2. In the present embodiment, a part of the electrode 5 specified forthe resistor is interposed between the heat resistor 2 and the substrate1. Alternatively, it may be different from the present embodiment that apart of the heat resistor 2 is interposed between the electrode 5specified for the resistor and the substrate 1.

As shown in FIG. 2 and FIG. 3, the electrode 5 specified for theresistor includes a bond pad 511 for a first resistor, a connectingportion 512 for the first resistor, a bond pad 516 for a secondresistor, and a connecting portion 517 for the second resistor.

The bond pad 511 for the first resistor is a rectangular portion. Thepower from outside of the heater 101 is supplied to the bond pad 511 forthe first resistor. The connecting portion 512 for the first resistor isconnected to the bond pad 511 for the first resistor. The connectingportion 512 for the first resistor is overlapped with a part of the heatresistor 2, and is connected to the heat resistor 2. More specifically,the connecting portion 512 for the first resistor is overlapped with afirst elongated portion 21 in the heat resistor 2, and is connected tothe first elongated portion 21 in the heat resistor 2. The connectingportion 512 for the first resistor has a shape of a band extending alongthe long side direction X of the substrate 1.

The bond pad 516 for the second resistor is a rectangular portion. Theconnecting portion 517 for the second resistor is connected to the bondpad 516 for the second resistor. The connecting portion 517 for thesecond resistor is overlapped with a part of the heat resistor 2, and isconnected to the heat resistor 2. More specifically, the connectingportion 517 for the second resistor is overlapped with a secondelongated portion 22 in the heat resistor 2, and is connected to thesecond elongated portion 22 in the heat resistor 2. The connectingportion 517 for the second resistor has a shape of a band extendingalong the long side direction X of the substrate 1. Along the short sidedirection Y of the substrate 1, the connecting portion 517 of the secondresistor is separated from the bond pad 516 of the second resistor.

In addition, a coupling portion 59 is formed on the heater 101 forcoupling the first elongated portion 21 and the second elongated portion22. The coupling portion 59 extends along the short side direction Y ofthe substrate 1. One end of the first elongated portion 21 is coupledwith one end of the second elongated portion 22 by the coupling portion59. The coupling portion is connected to both the first elongatedportion 21 and the second elongated portion 22. The coupling portion 59and bond pad 511 for the first resistor are formed on opposite sides ofthe heat resistor 2.

As shown in FIG. 2, FIG. 3 and FIG. 7, the substrate 1 includes aheating zone Z21 and a non-heating zone Z22.

The heating zone Z21 is in the long side direction X of the substrate 1.The heating zone Z21 is also a zone between the heat resistor 2 and theelectrode 5, and overlapped with the heat resistor 2. In the presentembodiment, as shown in FIG. 4, an end of the connecting portion 512 forthe first resistor is coincident with the boundary between theheat-generating zone Z21 and the non-heat-generating zone Z22.Similarly, an end of the connecting portion 517 for the second resistoris coincident with the boundary between the heat-generating zone Z21 andthe non-heat-generating zone Z22.

The non-heating zone Z22 is a different zone from the heating zone Z21.The non-heating zone Z22 is adjacent to the heating zone Z21 in the longside direction X. In the present embodiment, the bond pad 511 for thefirst resistor, the connecting portion 512 for the first resistor, thebond pad 516 for the second resistor and the connecting portion 517 forthe second resistor are disposed in the non-heating zone Z22.

The protection layer 7 shown in FIG. 1, FIG. 2, and FIG. 4 to FIG. 7covers the heat resistor 2. In addition, the protection layer 7 isadjacent to the heat resistor 2. Further, the protection layer 7 coversa portion of the electrode 5. Specifically, the protection layer 7covers the connecting portion 512 of the first resistor and theconnecting portion 517 of the second resistor. The electrode 5 for theresistor is partially exposed from the protection layer 7. Specifically,the bond pad 511 for the first resistor and the bond pad 516 for thesecond resistor are exposed from the protection layer 7. The protectionlayer 7 includes, for example, glass or polyimide, etc.

As shown in FIG. 1, in the device 800, the substrate main surface 11side of the substrate 1 is toward the platen roller 801. Therefore, theheat resistor 2 is disposed between the substrate 1 and the platenroller 801. On the other hand, a thermistor 861 is arranged on thesubstrate back surface 12 for detecting a temperature of the substrate1.

Subsequently, the effects of the heater 101 are illustrated.

FIG. 8 shows the relationship between the dimension of distance L1 anddistance L2 and the endurance time Te. At this time, the substrate 1includes aluminum oxide or zirconium oxide, and the thickness t is setas 0.4 mm˜1.0 mm. The endurance time Te is defined as while a powerenergy is applied to the heater 101, the time till the substrate 1 orthe heat resistor 2 is confirmed as failed. Such test is performed undera situation that the applied power energy is relatively large, forexample, being about 1823 W.

As shown in FIG. 8, while distance L1 and distance L2 are more than 0.7mm, the endurance time Te is approximately less than 4.5 sec. On theother hand, while distance L1 and distance L2 are less than 0.7 mm, theendurance time Te is approximately more than 4.5 sec. Additionally,while distance L1 and distance L2 are less than 0.7 mm, when thedistance L1 and the distance L2 are reduced, the degree of increase ofthe endurance time Te is more than the degree that while distance L1 andthe distance L2 are more than 0.7 mm. As a result, if the distance L1and the distance L2 are less than 0.7 mm, failures of the substrate 1 orthe heat resistor 2 can be prohibited. In addition, while the ratio ofthe distance L1 and the distance L2 to the thickness t of the substrate1 is less than 1.75, the effect of prohibiting failures is achieved.

Additionally, in the test shown in FIG. 8, the short side directiondimension W of the substrate 1 is 3 mm˜15 mm. Accordingly, under thesituation that the ratio of the distance L1 and the distance L2 to theshort side direction dimension W is less than 0.23, the effect ofprohibiting failures is achieved.

If the distance L1 and the distance L2 are set to be more than 0.05 mm,unreasonable difficulties during fabrication of the first elongatedportion 21 and the second elongated portion 22 or the protection layer 7can be prevented. If taking this into consideration, the ratio of thedistance L1 and the distance L2 to the thickness t is preferably morethan 0.05 and less than 1.75. In addition, the ratio of the distance L1and the distance L2 to the short side direction dimension W ispreferably more than 0.003 and less than 0.23.

FIG. 9 shows the relationship between the dimension of distance L3 andthe endurance time Te. At this time, the substrate 1 includes aluminumoxide or zirconium oxide, and the thickness t is set as 0.4 mm˜1.0 mm.The endurance time Te is the same as that in FIG. 8.

As shown in FIG. 9, while distance L3 is more than 3.8 mm, the endurancetime Te is approximately less than 5.0 sec. On the other hand, whiledistance L3 is less than 3.8 mm, the endurance time Te is approximatelymore than 5.0 sec. Accordingly, if the distance L3 is less than 3.8 mm,failures of the substrate 1 or the heat resistor 2 can be prohibited. Inaddition, while the ratio of the distance L1 and the distance L2 to thethickness t of the substrate 1 is less than 9.5, the effect ofprohibiting failures can be achieved. Taking 0.05 mm as the lower limitof the distance L3 into consideration, the ratio of the distance L1 andthe distance L2 to the thickness t of the substrate 1 is preferably morethan 0.05 and less than 9.5.

In addition, in the test result shown in FIG. 9, the short sidedirection dimension W of the substrate 1 is 3 mm˜15 mm. Therefore, underthe situation that the ratio of the distance L3 to the short sidedirection dimension W is more than 0 and less than 1.27, the effect ofpreventing damages on the substrate 1 and the heat resistor 2. Taking0.05 mm as the lower limit of the distance L3 into consideration, theratio of the distance L3 to the short side direction dimension W of thesubstrate 1 is preferably more than 0.003 and less than 1.27.

As the material of the substrate 1, aluminum oxide or zirconium oxide isused, such that the cost of the heater 101 can be reduced.

FIG. 10 and FIG. 11 show another embodiment of the present invention. Inaddition, in these figures, implementations or elements the same as orsimilar to those in the above embodiments are indicated by the samereference numerals.

FIG. 10 and FIG. 11 show a heater according to the second embodiment ofthe present invention. The difference between the heater 102 of thepresent embodiment and the heater 101 mentioned above is that the heatresistor 2 is only includes a first elongated portion 21.

FIG. 10 is a top view showing a main portion of the heater 102, and theprotection layer 7 is omitted. FIG. 11 is a cross-sectional view alongline XI-XI in FIG. 10.

The first elongated portion 21 extends in a longitudinal shape along thelong side direction X of the substrate 1. In the present embodiment, asshown in FIG. 11, the distances between two lateral ends in the shortside direction Y of the first elongated portion 21 and two edges in theshort side direction Y of the substrate 1 are respectively distance L1.

In the present embodiment, a ratio of the distance L1 to the thickness tof the substrate 1 is also more than 0 and less than 1.75, andpreferably more than 0.05 and less than 1.75. The distance L1 is 0mm˜0.7 mm, and preferably 0.05mm˜0.7mm. In addition, the ratio of thedistance L1 to the short side direction dimension W is more than 0 andless than 0.23, and preferably more than 0.003 and less than 0.23. Inaddition, owing to the limit to fabricate the first elongated portion 21or the protection layer 7, the lower limit of the distance L1 ispreferably 0.05 mm.

An electrode 5 for a resistor in the present embodiment includes a pairof bond pads 511 for a first resistor and a pair of connecting portions512 for the first resistor. The pair of bond pads 511 for the firstresistor are formed on a substrate main surface 11 of a substrate 1, andarranged laterally at two sides of the substrate 1 in the long sidedirection X. The connecting portions 512 pair for the first resistorconnects the pair of bond pads 511 for the first resistor with two endsof the first elongated portion 21 (the heat resistor 2) in the long sidedirection X.

According to this embodiment, failures of the substrate 1 or the heatresistor 2 can also be prohibited.

The heater of the present invention is not limited to the aboveembodiments. The specific constitution of each part of the heater in thepresent invention can be freely designed and varied.

What is claimed is:
 1. A heater, comprising: a substrate in alongitudinal shape; a heat resistor, formed on the substrate; and anelectrode for resistor, formed on the substrate and in contact with theheat resistor; wherein the heat resistor includes a first elongatedportion, and the first elongated portion extends along a long sidedirection of the substrate and is disposed in a side in a first shortside direction, which is one of short side directions of the substrate,and wherein a ratio of a distance between the first elongated portionand an edge of the substrate in the first short side direction, to athickness of the substrate is more than 0 and less than 1.75.
 2. Theheater according to claim 1, wherein the ratio of the distance betweenthe first elongated portion and the edge of the substrate in the firstshort side direction, to the thickness of the substrate is more than0.05 and less than 1.75.
 3. The heater according to claim 1, wherein theheat resistor further comprises a second elongated portion, the secondelongated portion extends along the long side direction of the substrateand is disposed in a side in a second short side direction, which isopposite to the first short side direction; the first elongated portionand the second elongated portion are separated in a short side directionof the substrate, a ratio of a distance between the second elongatedportion and an edge of the substrate in the second short side direction,to the thickness of the substrate is more than 0 and less than 1.75. 4.The heater according to claim 3, wherein the ratio of the distancebetween the second elongated portion and the edge of the substrate inthe second short side direction, to the thickness of the substrate ismore than 0.05 and less than 1.75.
 5. The heater according to claim 3,wherein the distance between the first elongated portion and the edge inthe substrate on the first short side direction is 0 mm˜0.7 mm.
 6. Theheater according to claim 5, wherein the distance between the firstelongated portion and the edge of the substrate in the first short sidedirection is 0.05 mm˜0.7 mm.
 7. The heater according to claim 3, whereinthe distance between the second elongated portion and the edge of thesubstrate in the second short side direction is 0 mm˜0.7 mm.
 8. Theheater according to claim 7, wherein the distance between the secondelongated portion and the edge of the substrate in the second short sidedirection is 0.05 mm˜0.7 mm.
 9. The heater according to claim 3, whereina ratio of a distance between the first elongated portion and the secondelongated portion in the short side direction, to the thickness of thesubstrate is more than 0 and less than 9.5.
 10. The heater according toclaim 9, wherein the ratio of the distance between the first elongatedportion and the second elongated portion in the short side direction, tothe thickness of the substrate is more than 0.05 and less than 9.5. 11.The heater according to claim 9, wherein the distance between the firstelongated portion and the second elongated portion in the short sidedirection is more than 0 mm and less than 3.8 mm.
 12. The heateraccording to claim 11, wherein the distance between the first elongatedportion and the second elongated portion in the short side direction ismore than 0.05 mm and less than 3.8 mm.
 13. The heater according toclaim 3, wherein the thickness of the substrate is 0.4˜1.0 mm.
 14. Theheater according to claim 3, wherein a ratio of the distance between thefirst elongated portion and the edge of the substrate in the first shortside direction, to a dimension of the substrate in the short sidedirection is more than 0 and less than 0.23.
 15. The heater according toclaim 14, wherein the ratio of the distance between the first elongatedportion and the edge of the substrate in the first short side direction,to the dimension of the substrate in the short side direction is morethan 0.003 and less than 0.23.
 16. The heater according to claim 14,wherein a ratio of the distance between the second elongated portion andthe edge of the substrate in the second short side direction, to thedimension of the substrate on the short side direction is more than 0and less than 0.23.
 17. The heater according to claim 16, wherein theratio of the distance between the second elongated portion and the edgeof the substrate in the second short side direction, to the dimension ofthe substrate on the short side direction is more than 0.003 and lessthan 0.23.
 18. The heater according to claim 14, wherein a ratio of adistance between the first elongated portion and the second elongatedportion in the short side direction, to the dimension of the substratein the short side direction is more than 0 and less than 1.27.
 19. Theheater according to claim 18, wherein the ratio of the distance betweenthe first elongated portion and the second elongated portion in theshort side direction, to the dimension of the substrate in the shortside direction is more than 0.03 and less than 1.27.
 20. The heateraccording to claim 14, wherein dimension of the substrate in the shortside direction is 3.0 mm˜15.0 mm.
 21. The heater according to claim 3,wherein the substrate includes aluminum oxide or zirconium oxide. 22.The heater according to claim 3, further comprising a protection layercovering the heat resistor.
 23. The heater according to claim 22,wherein the protection layer covers the first elongated portion, thesecond elongated portion and at least a portion of the electrode. 24.The heater according to claim 23, wherein the electrode includes a bondpad for a first resistor and a bond pad for a second resistor, whereinthe bond pad for the first resistor and the bond pad for the secondresistor are exposed from the protection layer.
 25. The heater accordingto claim 24, wherein the electrode includes a connecting portion for thefirst resistor and a connecting portion for the second resistor, theconnecting portion for the first resistor is connected to the bond padfor the first resistor and in contact with the first elongated portion,the connecting portion for the second resistor is connected to the bondpad for the second resistor and in contact with the second elongatedportion, the connecting portion for the first resistor and theconnecting portion for the second resistor are covered by the protectionlayer.
 26. The heater according to claim 22, wherein the protectionlayer includes glass.
 27. The heater according to claim 1, wherein theheat resistor includes AgPd, nickel-chromium alloy, or ruthenium oxide.